Polymorphisms in DNA base excision repair genes ADPRT and XRCC1 and risk of lung cancer

Adenosine diphosphate ribosyl transferase (ADPRT) and Xray repair cross-complementing I (XRCC1) are two major DNA base excision repair (BER) proteins and act interactively in stimulating and executing BER processes. Polymorphisms of ADPRT Va1762Ala and XRCC1 Arg399Gln have been associated with altered protein function and BER activity. This case-control study examined the contribution of these two polymorphisms, alone and in combination, or in interaction with smoking, to the risk of developing lung cancer. We estimated the risk of lung cancer associated with these polymorphisms in 1,000 cases and 1,000 cancer-free controls using logistic regression models. Subjects having the ADPRT Ala/Ala genotype had an odds ratio (OR) of 1.68 [95% confidence interval (95% CI), 1.27-2.23] compared with those having the Val/Val genotype. A greater than multiplicative joint effect between the ADPRT polymorphism and smoking was observed. The ORs (95% Cl) of the Ala/Ala genotype for nonsmokers and smokers who smoked less than or equal to16, 16 to 28, or >28 pack-years were 1.13 (0.79-1.62), 1.35 (0.68-2.70), 2.46 (1.35-4.51) or 17.09 (8.15-35.83), respectively (P trend test < 0.001). Gene-gene interaction of ADPRT and XRCC1 polymorphisms increased risk of lung cancer in a supermultiplicative manner (OR for the presence of both ADPRT 762Ala/Ala and XRCC1 399Gln/Gln genotypes, 5.91; 95% Cl, 2.09-16.72), although the XRCC1 polymorphism itself was not associated with the risk. In conclusion, the ADPRT Va1762Ala polymorphism plays an important role in smoking-related lung cancer and the XRCC1 Arg399Gln polymorphism may serve as a risk modifier.